1. Technical Field
This relates to support fixtures for restraining a workpiece during a machining operation, and, more particulary, to adjustable support fixtures for precisely and accurately bringing the workpiece, and particularly a flat surface thereon, into a predetermined oriention relative to the machining device.
2. Background Art
Due to the expense associated with purchasing new engine heads and blocks, and in the interest of recycling the plentiful quantities of salvageable heads and blocks available, industries across the United States produce thousands of rebuilt engines daily using refurbished heads and blocks. A key process that frequently must be performed when reconditioning a workpiece such as an engine head or block is the precise remilling or regrinding of the face, i.e., the gasket surface of the head or the deck surface of the block. Cutting precision on the order of thousandths of an inch is necessary to reestablish the tight seal required when the workpiece is reattached to the engine along this facial surface. Furthermore, it is desirable to remove only the minimum amount of material necessary to produce a planar face when performing the cutting process so as to alter the compression ratio of the engine as little as possible.
The equipment necessary to perform the cutting process includes a grinding or milling machine used in conjunction with support means to which the workpiece is mounted during the grinding or milling operation, the support means having adjustable means for moving the face into contact with the cutting portion of the grinding or milling machine. The Neff U.S. Pat. No. 3,572,680 discloses support means including a table 14 having means for adjusting the table 14, but only in the horizontal plane. Such a limitation of the adjusting means makes the device of the Neff patent unsuitable for the present machining needs.
Another prior art device of interest is in Hazelton and Einstein U.S. Pat. No. 1,273,365 which discloses support means including a table G, the support means having adjusting means including struts 14 on which the table G is mounted. The adjusting means serve to vertically dispose the table G between two preset positions. However, incremental vertical ajustment of the table G is not possible, making it impossible to perform the cutting process with the precision necessary to effectively recondition engine heads or blocks.
In Trevarrow U.S. Pat. No. 4,561,815 and Rottler et al. U.S. Pat. No. 4,789,279 wedge means are disclosed to impart vertical movement to a workpiece to align the workpiece with machining means. However, neither patent discloses means for tilting the workpiece about both of its horizontal axes. Furthermore, both the Trevarrow and Rottler devices require a skilled operator to carefully align the workpiece with the corresponding machining tool.
Another prior art device of interest is in Pevner et al. U.S. Pat. No. 3,807,034 which discloses means for imparting vertical movement to a table A by manually adjusting the table A about its horizontal axes. No means for automatically aligning the table are disclosed, thereby requiring a skilled operator to properly align the Pevner device each time a workpiece is mounted thereon.
It is therefore clear that prior art adjustable support devices fail to provide adjusting means that can assure that the amount of material removed during each cutting operation will be only the minimum amount necessary to yield a planar face. Furthermore, prior art adjustable support means are difficult and time consuming to set up, difficult and time consuming to adjust, and difficult and time consuming to operate, frequently requiring repeated adjusting and machining of a single workpiece surface. Consequently, prior art adjustable support means are labor intensive, require substantial operator expertise, are expensive to operate, and often produce an inferior product.